1. Field of the Invention
The invention relates to the supply of electrical energy to electrical components installed on board a motor vehicle.
2. Background of the Related Art
Modern motor vehicles comprise numerous auxiliary equipments essential for the functioning of the vehicle such as pumps and fans, or which provide additional comfort and safety, like air-conditioning installations, devices to prevent the locking of brakes, known as “ABS”, safety airbags, etc. Some of these devices, like the safety airbags, can be operated only electrically. Others, such as fans and pumps, can be driven mechanically by the engine itself. But their functioning is then linked with the engine speed, which constitutes a significant disadvantage.
That is why these equipments are increasingly driven by the intermediary of an electric motor that is itself powered by an electrical source of the vehicle. This makes it possible to decouple the functioning of these devices from that of the engine and, for example, to make them operate even when the engine is stopped or is running at idling speed. However, this tendency to actuate equipments of the vehicle increasingly in an electrical manner imposes a heavy load on the electrical source of the vehicle. The latter can therefore get into a state of availability that is inadequate for ensuring the functioning of vital safety devices (safety airbags, ABS). For example, if the electrical energy source is an accumulator battery, its charge can be insufficient.
That is why the need is felt for a device capable of protecting the electrical source of a vehicle in such a way that it always remains available to ensure certain essential safety functions.